The present invention relates to a plasma purification treatment or a plasma purification therapy which removes disease-causing constituents from the plasma of a patient suffering from diseases caused by those ailment causing constituents in his or her blood plasma.
Contained in human plasma are various proteins such as albumin, immunoglobulins (IgG, IgA, IgM) and fibrinogen and other constituents such as nucleic acid and lipids. Although their concentrations are controlled by the various mechanisms of the living body so as to maintain the balance of each system which they belong to, the balance of some system can be disturbed from internal or external causes, resulting in an abnormal increase or presence of particular constituents. This abnormal increase or presence of plasma constituents is known to cause various diseases.
Known as such type of diseases are immunologically caused kidney diseases (acute renal transplant rejection, GOODPASTURE syndrome, etc.), collagen diseases (chronic rheumatoid arthritis, systemic lupus erythematosus, myasthenica gravis, Graves disease, autoimmune hemolytic anemia, Sjoegren syndrome, etc.), plasma proteins abnormality diseases (multiple myeloma, primary macrogrobulinemia, etc.), cholesterol (low-density lipoprotein in particular) metabolic error disease (familial cholesterolemia), liver diseases (bilirubinemia, etc.), and poisonings.
Recently, so called plasma exchange therapy which removes plasma from a patient and returns fresh or frozen plasma or albumin preparation to the patient for replenishment has been applied to clinical treatment and its therapeutic value has been confirmed. However, this plasma exchange therapy has a problem that it needs a large volume of substitute liquid to exchange with the plasma of a patient. Further, when an albumin preparation is used as the replacement liquid, all the necessary constituents of plasma cannot be supplied. On the other hand, when fresh or frozen plasma is used as the substitute liquid, since it is prepared using plasma of donors, there is a high risk of infection of hepatitis and acquired immunodeficiency syndrome (AIDS) and of outbreak of allergy.
To solve the above problems, a plasma purification treatment has been proposed which removes disease-causing constituents alone from the plasma of a patient and returns the treated plasma to the patient. This plasma purification treatment draws blood from a patient by means of a pump or other appropriate means at the rate of about 100 ml per minute, separates the plasma and the blood cells of the whole blood by a centrifuge or membrane filters, removes the causative constituents from the plasma, joins the treated plasma and the blood cells together, then returns the blood back to the patient. There are several methods for removing causative constituents from plasma: salting-out method which adds salting-out agents to plasma and precipitates causative constituents (for example, high-molecular weight proteins) by the difference of solubility (U.S. Pat. No. 4,321,192); adsorbing method which adsorbs causative constituents using adsorbents with specific adsorbing capability to them (U.S. Pat. No. 4,814,077); cooling-out method which cools plasma and precipitates causative constituents (U.S. Pat. No. 4,350,156); filtering method which removes causative constituents by means of filters which retain causative constituents and larger molecular weight constituents (U.S. Pat. No. 4,350,156).
Purification of plasma by these method in which blood is circulated in an extracorporeal circuit through the processing steps has problems as described below.